The dramatic plunge in Windows XP's market share has continued in the latest numbers from Netmarketshare, released today (Monday). These show Windows XP dropping another 3.6 percentage points from 17.18 to 13.57 percent of the market, as measured by unique visitors to a global selection of websites. Meanwhile, Windows 8.1 has grown from 10.92 to 12.01 percent, and Windows 8 from 5.88 to 6.55 percent. This puts Windows 8/8.1 ahead of Windows XP by 18.56 to 13.57 percent.
It's remarkable for an operating system's market share to drop by 3.6 points in a single month. This is, after all, bigger than the current market share of Apple's Mac OS X 10.9 (2.79 percent). And as with similar remarkable drops revealed last month, I'm pretty sure it's not real. (See: Windows 8, 8.1 about to overtake plunging XP, on Netmarketshare's latest numbers)
As my colleague Ed Bott pointed out, what happened last month was that Netmarketshare decided that it had got its numbers wrong, due to the inclusion of certain Chinese websites that were visited almost exclusively by Windows XP users. It decided to silently rebalance them closer to reality, and that might have worked. An astonishing number of tech websites simply reported the new numbers as though nothing unusual had happened.
As I pointed out last month, the new numbers rewrite the Windows XP story. At the start of this year, it had roughly three times as many users as Windows 8/8.1. Companies that planned to hang on to this defunct operating system could point to Netmarketshare's numbers as evidence of a very large recalcitrant user base — perhaps half a billion users — rejecting those new-fangled Live Tiles. The latest numbers show Windows 8/8.1 being adopted very quickly while XP plunges into irrelevance.
Whether either of these narratives matches reality is a tricky question. However, it's more likely that today's numbers are right and the old ones wrong. Otherwise, Netmarketshare wouldn't go through the pain and public embarrassment.
Whether the adjustment is complete is another matter: you'll have to wait for next month. Either way, it must be obvious to even the dimmest tech journalist that Netmarketshare's numbers are not accurate to two decimal places. At the moment, I don't think I'd claim they're accurate to two percentage points. I'd simply say what I've said several times before: they're a good guide to market trends, and they're still the best free numbers we've got.
For the record, Microsoft Windows 7 has continued to gain market share as businesses have continued to migrate from XP. It's now up to 53.7 percent — more than half the market. Windows XP has continued to decline, falling by half since April, from 26.29 to 13.57 percent. Windows 8.1 has gained around 10 percentage points in the past year (from 2.64 to 12.10 percent) while Windows 8 has held steady (6.66 to 6.55 percent).
Overall, Windows has actually increased its market share this year, from 90.74 to 91.48 percent, on Netmarketshare's numbers. Both Mac OS X (down from 7.66 to 7.27 percent) and Linux (down from 1.59 to 1.25 percent) have lost a little ground. I think the differences are too small to be meaningful.
On the Mac front, OS X 10.10 (2.66 percent) and 10.9 (2.79 percent) are now level pegging with Windows Vista (2.65 percent).